We all know it or expect it—coffee makes you poop. But how true is this? Well, according to a recent study, it’s confirmed that this bitter drink does help you to go.

But why? It’s been known since small studies in the late 1990s that coffee appears to help you poop. This study found that drinking a cup of joe made people feel the need to go in just a few minutes! And sure, caffeine is a catalyst. But both caffeinated and decaf coffee had pretty similar colon stimulatory effects. Like other foods and beverages, coffee takes around an hour to move through your intestinal tract to your colon. So how does it manage to come into effect so quickly?

Conversely, a different study from the 1990s had 92 young adults fill out a questionnaire on the effects of coffee on their bowel habits. In their own opinion, only 29% of these respondents reported an increased “desire to defecate”, 63% of which were female.

This has led some researchers to hypothesize that coffee’s urge to make you poop is nothing to do with the caffeine but is a result of the signals coffee triggers in your brain—the “gut-brain axis”. This idea is that coffee sends your brain a message to clear out the colon.

Yet another study from the late 1990s discovered that drinking eight ounces of coffee stimulated contractions in a person’s colon similar to those you’d expect after consuming a 1,000 calorie meal. But unfortunately, this outsized effect of coffee also causes some of our essential digestive hormones, like cholecystokinin and gastrin, to spike after we drink it.

A 2020 analysis of seven clinical trials concluded that drinking coffee allowed colorectal and gynecological surgery patients to tolerate solid foods 10 to 31 hours sooner, respectively. Joe made their first post-surgery poop come sooner too—15 to 18 hours sooner. Even just a couple of sips had a significant effect.

Of course, you should avoid becoming reliant on coffee for your morning poop. Instead, some fiber in the morning from fruit, vegetables, or cereal can go a long way in helping you go. But if you’re struggling, it’s official - coffee is an excellent way to help you poop!